Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant’s reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.

Book Chapter

In press

Tracking phenology in the tropics and inIndia: the impacts of climate change

We evaluated the role of large avian frugivores in a plant‐disperser community by a) determining whether the plant‐disperser community was modular, with a distinct community of large frugivores (thereby highlighting their importance), b) determining relative qualitative and quantitative roles played by large‐bodied frugivores vis‐à‐vis other frugivores and c) determining impacts of large‐bodied frugivore loss on the plant‐disperser community. The study was carried at a tropical forest site in north‐east India which is part of the Eastern Himalaya Biodiversity Hotspot. We collected tree watch data (2055 h) from 46 tree species, which represented 85% of tree species that are predominantly bird‐dispersed in the area. We found that the plant‐disperser community was modular, with a distinct module of large‐seeded tree species and large frugivores. Intermediate‐sized frugivores such as barbets and bulbuls were the most connected, while large‐sized frugivores, such as hornbills and imperial‐pigeons were moderately well‐connected. Qualitative and quantitative roles played by different dispersers varied across the gradient of frugivore body size. Hornbills, the largest avian frugivores, consumed a significantly greater number of fruits and swallowed larger proportions of fruits compared to other avian groups. In comparison to similar‐sized frugivores, imperial‐pigeons fed on larger‐sized fruits, highlighting their importance for dispersal of large‐seeded plants. Under simulated extinction scenarios, larger extinction cascades weren't necessarily caused by larger frugivores, however, extinctions of certain large‐bodied frugivores (hornbills, imperial‐pigeons) caused extinction cascades. Integrating information from networks and seed dispersal effectiveness approaches enabled a better understanding of large frugivore role in a plant‐disperser community. While large‐bodied frugivores may not be playing a central role in plant‐disperser communities, they are crucial as seed dispersal service providers for large‐seeded plants. In conjunction with the reported local extinctions of large frugivores like hornbills from the south Asian region, this study's findings highlight the irreplaceable quantitative and qualitative impacts that tropical plant communities are likely to experience in the future.

Sympatric breeding of Sarus Cranes (Antigone
antigone) and Brolga (A. rubicunda)
occurs only in northern Queensland, Australia but factors contributing to this
unique sympatry are unknown. Large-scale developments currently planned in this
region, with potentially major impacts on cranes, create an urgent need to understand
the ecological requirements of each crane species. We carried out a multi-floodplain
landscape-scale survey during April-May 2017 and derived metrics for several ecological
aspects for the first time for both crane species. The abundance of the two
species differed between the floodplains. Both crane species synchronised
nest-initiation with rainfall (November to March). Breeding success was higher
than past estimates anywhere, with 60% of Sarus Crane pairs and 50% of Brolga
pairs fledging chicks. Sarus Cranes preferred four riverine Eucalyptus-dominated regional
ecosystems, with 10% using open habitats. Brolgas preferred two non-wooded
regional ecosystems, but 32% shared Eucalyptus-dominated
regional ecosystems with Sarus Cranes. Stable isotope analyses revealed Sarus diet
to be comprised of more diverse vegetation than Brolgas, while Brolgas fed across
a wider range of trophic levels. The ecology of Gulf cranes closely matched
habits of Sarus Cranes in south Asia, despite disparate conditions suggesting
considerable species plasticity. The diverse habitats of the Gulf and varying diet
appear to facilitate the cranes’ sympatry, and our study provides basic data
for developing long-term conservation plans in the face of development
activities.

Accurate assessments of the status of threatened species and their conservation planning require reliable estimation of their global populations and robust monitoring of local population trends. We assessed the adequacy and suitability of studies in reliably estimating the global snow leopard (Panthera uncia) population. We compiled a dataset of all the peer-reviewed published literature on snow leopard population estimation. Metadata analysis showed estimates of snow leopard density to be a negative exponential function of area, suggesting that study areas have generally been too small for accurate density estimation, and sampling has often been biased towards the best habitats. Published studies are restricted to six of the 12 range countries, covering only 0.3–0.9% of the presumed global range of the species. Re-sampling of camera trap data from a relatively large study site (c.1684 km2) showed that small-sized study areas together with a bias towards good quality habitats in existing studies may have overestimated densities by up to five times. We conclude that current information is biased and inadequate for generating a reliable global population estimate of snow leopards. To develop a rigorous and useful baseline and to avoid pitfalls, there is an urgent need for (a) refinement of sampling and analytical protocols for population estimation of snow leopards (b) agreement and coordinated use of standardized sampling protocols amongst researchers and governments across the range, and (c) sampling larger and under-represented areas of the snow leopard's global range.

Jostling for column space among reports of new snakes, reptiles and frogs discovered, are a particularly delightful and large group of spiders called jumping spiders. These little arachnids are known for their astonishing array of cognitive abilities and are considered model organisms to study behaviour, as well as answer theoretical questions about communication, foraging, courtship, mating and parental care.

The roosting
ecology of most waterbird species is poorly known and even less is known from southern
Asia, where many species inhabit human-modified areas. Roosting ecology of the
Black-headed Ibis (Threskiornis
melanocephalus) was studied in urban and rural settings in southern
Rajasthan, India. Analyses focused on assessing whether site characteristics
varied between nest sites, urban and rural roost sites, and paired sites (i.e.,
a waterbird roost site near Black-headed Ibis roosts but without Black-headed
Ibis). Additionally, the hypothesis that factors affecting Black-headed Ibis
numbers at roosts would be similar at urban and rural sites was tested. Tree
characteristics (canopy cover, girth at breast height) were different (P < 0.05) between nest and roost
sites. Urban roost sites experienced 2.3 times greater disturbance than rural
roost sites. Paired site characteristics were similar to urban roost sites
(multi response permutation procedure, significance
of δ = 0.3), but were dissimilar to rural roost sites. Co-occurring
roosting bird assemblages were significantly different between roosts and
paired sites (significance of δ < 0.01)
in urban and rural settings. Black-headed Ibis numbers at urban roosts were
influenced by multiple variables, but models showed considerable ambiguity at
rural sites. Results strongly suggest that including roost sites in a species
status assessment is important.

Popular Article

2019

பறவைகளை வடிக்கும் இயற்கை ஓவியர் (Interview with Sivakumar, An artist and birder from The Forest Way, Tiruvannamalai)

We evaluated the role of large avian frugivores in a plant‐disperser community by a) determining whether the plant‐disperser community was modular, with a distinct community of large frugivores (thereby highlighting their importance), b) determining relative qualitative and quantitative roles played by large‐bodied frugivores vis‐à‐vis other frugivores and c) determining impacts of large‐bodied frugivore loss on the plant‐disperser community. The study was carried at a tropical forest site in north‐east India which is part of the Eastern Himalaya Biodiversity Hotspot. We collected tree watch data (2055 h) from 46 tree species, which represented 85% of tree species that are predominantly bird‐dispersed in the area. We found that the plant‐disperser community was modular, with a distinct module of large‐seeded tree species and large frugivores. Intermediate‐sized frugivores such as barbets and bulbuls were the most connected, while large‐sized frugivores, such as hornbills and imperial‐pigeons were moderately well‐connected. Qualitative and quantitative roles played by different dispersers varied across the gradient of frugivore body size. Hornbills, the largest avian frugivores, consumed a significantly greater number of fruits and swallowed larger proportions of fruits compared to other avian groups. In comparison to similar‐sized frugivores, imperial‐pigeons fed on larger‐sized fruits, highlighting their importance for dispersal of large‐seeded plants. Under simulated extinction scenarios, larger extinction cascades weren't necessarily caused by larger frugivores, however, extinctions of certain large‐bodied frugivores (hornbills, imperial‐pigeons) caused extinction cascades. Integrating information from networks and seed dispersal effectiveness approaches enabled a better understanding of large frugivore role in a plant‐disperser community. While large‐bodied frugivores may not be playing a central role in plant‐disperser communities, they are crucial as seed dispersal service providers for large‐seeded plants. In conjunction with the reported local extinctions of large frugivores like hornbills from the south Asian region, this study's findings highlight the irreplaceable quantitative and qualitative impacts that tropical plant communities are likely to experience in the future.